This invention relates generally to an nozzle and more specifically to a nozzle tip for a fuel injector used with the internal combustion engine.
Manufacturers of internal combustion engines are continuously attempting to improve on the efficiency and emissions output of internal combustion engines. In diesel engines, a large amount of research has been done to reduce NOx output of an engine, through the use of improved fuel injectors and injection timing. Typically, combustion takes place over approximately 40 to 50 degrees of crankshaft rotation. A nozzle tip for a fuel injector in a typical modern diesel engine includes an end portion, the end portion includes a plurality of nozzle openings. High pressure fuel is forced into the end portion and sprayed into the combustion chamber as the piston nears top dead center. The nozzle openings are oriented to spray fuel at an angle of 60 to 80 degrees from a longitudinal axis of the injector.
Research has revealed that NOx emissions can be greatly reduced at partial load through a Homogeneous Charge Compression Ignition (HCCI). This is accomplished by injecting fuel into the cylinder at a much earlier stage in the combustion cycle. In this case, earlier, refers to the piston being farther from the cylinder head during the compression stroke of the engine, as the piston moves toward the cylinder head. The early injection permits fuel and air to more thoroughly mix, because in part there is a larger area between the top of the piston and the cylinder head. Having fuel and air more thoroughly mixed creates more complete combustion.
Using a conventional injector tip configuration to achieve Homogeneous Charge Compression Ignition operation of an internal combustion engine results in fuel being sprayed in an undesirable pattern causing inadequate mixing. For example fuel may cling to the cylinder walls and other surfaces and not properly mix with air. This is because of the direction of the nozzle openings is toward the cylinder walls and the piston is so far from the fuel injector. By changing the angle of the nozzles in relation to the longitudinal axis, fuel can be directed toward the top surface of the piston. Changing the angle of the nozzle openings creates a new problem, fatigue life of the nozzle cavity at the entrance of the nozzle opening may be reduced using conventional tip geometry.
The present invention is directed to overcoming one or more of the above identified problems.
In a one aspect of the present invention, a nozzle tip for a fuel injector is provided. The fuel injector includes a longitudinal axis. The nozzle tip includes the end portion having a inner surface and a outer surface. A plurality of nozzle openings are disposed through said end portion and have a central axis. Each of the nozzle openings at an angle between the central axis and longitudinal axis of between 5 and 10 degrees.